The energy landscapes of bidisperse particle assemblies on a sphere

Ballard, Alexander F., Panter, Jack R. ORCID: https://orcid.org/0000-0001-8523-7629 and Wales, David J. (2021) The energy landscapes of bidisperse particle assemblies on a sphere. Soft Matter, 17 (40). pp. 9019-9027. ISSN 1744-683X

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Abstract

The interplay between crystalline ordering, curvature, and size dispersity make the packing of bidisperse mixtures of particles on a sphere a varied and complex phenomenon. These structures have functional significance in a broad range of systems, such as cellular organisation in spherical epithelia, catalytic activity in binary colloidosomes, and chemical activity in heterofullerenes. In this contribution, we elucidate the potential energy landscapes for systems of repulsive, bidisperse particles confined to the surface of a sphere. It is commonly asserted that particle size dispersity destroys ordered arrangements, leading to glassy landscapes. Surprisingly, across a range of compositions, we find highly ordered global minima. Moreover, a minority of small particles is able to passivate defects, stabilising bidisperse global minima relative to monodisperse systems. However, our landscape analysis also reveals that bidispersity introduces numerous defective, low-lying states that are expected to cause broken ergodicity in corresponding experimental and computational systems. Probing the global minimum structures further, particle segregation is energetically preferred at intermediate compositions, contrasting with the approximate icosahedral global packing at either end of the composition range. Finally, changing the composition has a dramatic effect on the heat capacity: systems with low-symmetry global minima have melting temperatures an order of magnitude lower than monodisperse or high-symmetry systems. This observation may provide a further example of the principle of maximum symmetry: higher symmetry global minima exhibit a larger energy separation from the minima that define the high-entropy phase-like region of configuration space, raising the transition temperature.

Item Type: Article
Additional Information: Funding Information: The authors would like to acknowledge the encouragement and experimental work of Daria S. Roshal, Marianne Martin, Kirill Fedorenko, Virginie Molle, Stephen Baghdiguian, and Sergey B. Rochal, which promoted the development of this research. The authors also acknowledge Halim Kusumaatmaja for the original software development of the binary spherical systems used here. DJW gratefully acknowledges the EPSRC for financial support. Publisher Copyright: © The Royal Society of Chemistry 2021.
Uncontrolled Keywords: chemistry(all),condensed matter physics ,/dk/atira/pure/subjectarea/asjc/1600
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Depositing User: LivePure Connector
Date Deposited: 16 Sep 2022 13:36
Last Modified: 05 Oct 2022 00:20
URI: https://ueaeprints.uea.ac.uk/id/eprint/88388
DOI: 10.1039/d1sm01140e

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